C++ :: Defining Limits Over A Variable?
Oct 6, 2014
In a part of my code I'm defining limits over a variable which is in type of:
fftw_complex *i_phi
Then it is initialized as:
i_phi = (fftw_complex*) fftw_malloc(nx*ny* sizeof(fftw_complex));
The limits are defined as follows.
if ( creal(phi[i]) < 0.0 ) i_phi [i] = 0.0;
if ( creal(phi[i]) > 1.0) i_phi [i] = 1.0;
}
[Code]....
Printed numbers are showing a lot of fluctuation around limits eg, 1.00542, 1.0002 and -2.45829e-12.
I really have no idea why the limits are not applied for a lot of cells but my guess is that it's a problem from the CREAL function. Also I've changed the CREAL with __REAL__ but still the same problem shows up.
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Jun 18, 2012
If I DEFINE a global variable in two source files which belong to the same project, then there is a linker error "multiply defined symbols". But if I DEFINE a global variable in two source files which belong to the different projects, then it compiles fine. Why?
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Apr 4, 2014
Define a constant PI that has a value of 3.14159
- Create a double variable, Radius with an initial value of 10
- Create two double variables. Circum and Area, without initialization
- Using the following formulas, compute circumference and area of the circle:
circumference = pi * r * 2 (here, r means radius)
area = pi * r * r
- Display the result using three variables (numbers must come from variables)
- Expected output: (Don’t forget to display the period at the end of the first line)
Circle with radius of 10.
Circumference = 62.8318 Area = 314.159
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Oct 23, 2014
The question is: Define the class Counter. An instance of this class is used to count things, but the counter should never be less than 0 (non negative number). The member variable should be private. I realize what I'm suppose to be using but can't implement the member functions needed..
int main(){
int value;
cin >> value;
Counter myCounter(value);
for (int i = 1; i <= MAXLOOP; i++) {
myCounter.increment();
[Code] ....
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Oct 9, 2013
Im trying to choose a # between 1 and 1000 (can be 1 or 1000), error check it, but keep asking until I get the correct input.
#include<iostream>
using namespace std;
int main () {
int num;
bool goodNum;
goodNum = false;
while (!goodNum)
[code]....
This program analyzes a number, determining whether a number is prime or not, perfect or not, and output a list of all divisors for non-prime and perfect numbers.
Enter a number between 1 and 1000 then hit enter: 9000
You entered 9000.
Press any key to continue . . .
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Aug 22, 2014
I'm trying to perform a simple input operation, and check to make sure that whatever the user input is a valid input (is within data type bounds, is correct data type...). But when I get to ignoring the input, I keep getting an error.
unsigned short num;
while (true) {
std::cin >> num;
if (std::cin.fail()) {
num = 1;
[Code] ....
I don't fully understand why this error is here.
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Jan 4, 2015
I am trying to create a small set of filepath functions that I intend to compile across linux and windows (I prefer not to use a big library). I want to have a global constant PATH_SEPARATOR that depends on the OS environment. This is what I set at the top of header file.
Code:
#include <stdio.h>
const char PATH_SEPARATOR =
#ifdef _WIN32
'';
#else
'/';
#endif I was hoping to test this while compiling this in a linux environment using gcc, thusly:
Code:
int main (int argc, char const* argv[])
}
[code]....
where apparently, I seem not to be able to "set" a part of the code to have "_WIN32" defined. I don't know if I explained this clearly.
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Nov 15, 2013
I'm trying to define a 7x5 array in main and then use it in a different function that will fill that array with random floats between 0.0 and 1.0 and then use main to print the final, filled array.
Here is what I have so far:
Code:
#include <stdio.h>
#include <stdlib.h>
main () {
float array [7][5];
printf ("%f", array);
[Code] ....
I keep getting the following error message:
testinghw10.c: In function 'fillArray':
testinghw10.c:17: error: subscripted value is neither array nor pointer
I'm not sure what the problem is? Am I calling "array" variable incorrectly or did I initialize it wrong? Or something else entirely?
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Apr 9, 2015
Is there a way to define a 3 bit or 12 bit data type in C/C++. I need these for defining my own packet having different bit length fields.
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Jun 27, 2012
Say I have two projects A and B. A depends on B. If project A defines a macro to be 100 and project B defines the same macro to be 200. In project A, if I use this macro, what value would this macro be? Let's just forget macro is evil for the time being. Let's also forget that it is not good to define the same macro twice for the time being.
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Apr 6, 2013
I am looking at functions still and can't see the point in declaring the function at the top of the program, and then defining later i.e.
Code:
#include <iostream>
int add (int x, int y) {
return x + y;
[Code] .....
I obviously don't have much real world experience with this and am interested to see where declaring and defining later would be useful and/or beneficial.
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Jun 26, 2014
I want to create an unsigned arithmetic type that can hold a maximum size of 360. Without having to create a method.
It should be in such a manner that:
Code:
typedef uint8_t radius;
radius rotation = 0;
radius foo (radius rotation)
{ return --rotation;
}
returns 359, instead of 255, or 65535 or whatever max value the type I base my type on can hold.
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Mar 27, 2014
I am work on building a simple parse tree and the layout of my code look like this:
Headers
pt_node.hiterator.hparsetree.h
Source files
node.cppparsetree.cppmain.cpp
I am still relatively new to C++ , and have been advised to include function definition for the member function of both pt_node class and iterator class in the node.cpp file
I particular I have declare the following iterator.h:
inline bool operator ==(const tree_iterator& rhs);
which is defined in node.cpp as:
inline bool tree_iterator::operator==(const tree_iterator& rhs) {
return (node ==rhs.node);
}
However on building I receive the following error:
undefined reference to `dnkmat001::tree_iterator::operator==(dnkmat001::tree_iterator const&)'
Why is this occurring and what measure can I take to fix my code
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Feb 17, 2012
Suppose I have the following sample header file test.h
Code:
#include "myCommon.h"
class Test {
public:
Test();
vector<vector<vector<double>>> vI3(dim1, vector<vector<double>> (dim2, vector<double> (dim2, 0.0f)));
private:
fillVector();
}
In above test.h dim1 and dim2 are defined in a different header file, i.e. myCommon.h
Code:
const long dim1 = 40;
enum dimVector {
RED,
GREEN,
dim2
};
However, it gives the errors when I compile: variable "dim1" is not a type name and for variable "dim2" it complains about a duplicate parameter name.
The declarations of dim1 and dim2 should stay in myCommon.h. They can also be defined in myCommon.cpp if needed, but can't go into test.h.
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Dec 21, 2012
Programe #1
// file.h
class File {
public:
static const int var = 9;
};
[Code]....
Program#1 is running fine, but program#2 gives linker error:
error LNK2005: "int GlobalVar" (?x@@3HA) already defined in file.obj
I know the header files are never compiled. Then in the above case, how the compiler knows the definition of variable var, but not able to find the definition of GlobalVar? What is the difference between this two programs?
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Jun 22, 2012
I have an abstract class called Mbase and from it derived two classes: Sparse and Dense. Now I have an array in which its elements can be either Sparse or Dense. So, I delcared the array to have pointers to Mbase class. For example:
PHP Code:
Mbase** A;
Sparse* A1 = new Sparse;
Dense* A2 = new Dense;
A[1] = dynamic_cast<Mbase*>(A1);
A[2] = dynamic_cast<Mbase*>(A2);
Now, I have operator + defined in Sparse and Dense. but when I do
PHP Code:
A[1]+A[2]
I get that operator + is not defined for Mbase class. So, I tried to define it in the Mbase class
PHP Code:
class Mbase{
public:
void put()=0;
double get()=0;
Mbase operator +(Mbase A);
}
However, the last code does not compile complaining that it cannot declare a class of type abstract in Mbase operator +(Mbase A). I think this is because I am returning Mbase instance.
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Mar 16, 2013
Is it any different when using a class in my code. My previous code i define my struct like this
Code: #include <iostream>
#include <fstream>
#include <string>
struct{
[Code] .....
or do i still define it the same way at the top of my code.
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Apr 23, 2013
I am currently stuck on what I should do next in a program I am working on. These are my instructions:
Design, implement, and test a class for storing integer arrays "safely". The array should be able to hold any number of integers up to 100.
In the class header file "SafeArray.h" students must define the class and specify the constructor/destructor functions, the public methods and private variables. In the class implementation file "SafeArray.cpp" students must implement the following operations:
constructor - to initialize the object.
copy constructor - to copy an object.
destructor - to delete the object.
set - allow the user to set a value of the array at a particular location.
get - allow the user to get a value of the array at a particular location.
print - print out the array.
add - add the elements of one array to another.
subtract - subtract the elements of one array from another.
The output of my program is suppose to look like this:
Set q1: 2, 3, 4
Print q1: 2, 3, 4
Set q2: 1, 4, -2
Print q2: 1, 4, -2
Add q2 to q1
Print q1: 3, 7, 2
Get q1 at 1: 7
Here is the code I have so far.
*main.cpp*
#include <iostream>
#include "SafeArray.h"
using namespace std;
int main() {
// Declare a SafeArray object
Safe obj;
[Code] ....
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Sep 15, 2014
I'm struggling a bit to combine templates and operator overloading.
I'm writing a program that will be able to perform various matrix arithmetic at the end. However I'm stuck at the overloaded << and >> functions. I've defined them as I'm used to, without working with templates, however they are incorrect as I have defined them, and I'm not sure how to fix it.
I want to overload the stream insertion operator >> to read matrix data from either the keyboard or a file stream. I want to use >> to input a 3 x 3 matrix stored in a text file in the following format:
2 4 3
5 2 3
7 1 0
And similarly I want to overload the stream extraction operator << to output a matrix to the screen or file in the following format:
3 2 -1
1 -1 2
2 3 -1
Here is my work so far:
matrix.h
#ifndef MATRIX_H
#define MATRIX_H
#include <cassert>
#include <iostream>
using namespace std;
template <class T> class Matrix;
[Code] ....
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Jan 3, 2014
#include "stdafx.h"
#include <iostream>
#include <math.h>
using namespace std;
class Calc {
[Code] ....
when i built it, it showed the following errors:
1>------ Build started: Project: rough, Configuration: Debug Win32 ------
1> rough.cpp
1>e:c programs
ough
ough
ough.cpp(17): error C3872: '0xa0': this character is not allowed in an identifier
1>e:c programs
[Code] ....
Need sorting out the errors!!!
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Feb 11, 2013
How do i define user and lottery..
//Declarations
#include <iostream>
#include <cstdlib>
#include <ctime>
const int lotteryDigits = 10;
const int SIZE = 5;
const int Power = 1;
int generateLottery(int[], int, int);
[Code] ....
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Apr 13, 2014
I am currently having problems with defining an array of objects. I am getting 'redeclared as different kind of symbol' error message. The code is below
//MissionPlan.cpp
#include <iostream>
#include <string>
#include "MissionPlan.h"
#include "PointTwoD.h"
using namespace std;
//MissionPlan class implementation
[code]....
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Oct 20, 2013
i've defined an strcuct in .h file and i read its variable in a method in .cpp file ,but i'v got error.
.H file:
class myclass{
public:
struct opt_struct
[Code]....
when i declare the struct without static , it doesn't recognize my struct and with static i face linker error:
Error33error LNK1120: 1 unresolved externals
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May 18, 2013
This is a program I developed in which we had to define a class named BOOK with the data members and member functions as shown in the program..We have to:
(i) Make the user enter the values in the array BOOK.
(ii) Display the details that the user entered.
(iii) Search for a book from the array upon its Bno and display its details.
(iv) Search for a book from the array upon its Bname and display its details.
PROGRAM:
#include<iostream.h>
#include<conio.h>
#include<stdio.h>
#include<string.h>
class BOOK {
private:
int Bno;
char Bname[20];
[Code] .....
But while running it the compiler gives the errors as:
Line 43 to 48: Illegal character '' (0x5c)
Line 69: Undefined symbol 'Display'
Line 88: 'BOOK::Bno' is not accessible.
Line 89:'BOOK::Bname' is not accessible.
Line 90:'BOOK::Author' is not accesible.
Line 91:'BOOK::Price' is not accesible.
Line 108:'BOOK::Bno' is not accessible.
Line 109:'BOOK::Bname' is not accessible.
Line 110:'BOOK::Author' is not accesible.
Line 111:'BOOK::Price' is not accesible.
from 43 to 48..the line feed was also used at many other places but there it was not given as an error so why here?
Line 69: I defined the Display() function outside the class since it contained control structures, so what's the error then?
About the lines the rest of the error( the "not accessible" ones) I know these data members are not accessible because they are in private visibility mode. But then how to make them accessible? (Without putting them in public because it was a part of the question to create the data members in private).
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Oct 6, 2014
Basically, I have made a program which implements the platform specific layers (such as entry function, file loading, timing functions etc.) that gets compiled into a .exe (or platform equivalent).
But I want to make this portable and reusable across other projects, so the entry function for the platform will call the function "AppMain" which is the generic main function that is not reliant on the underlying platform etc. (i.e defined in a .h file that the project module will implement).
Ideally I would want to build the AppMain code into its own library. However, This AppMain code would want access to the Platform functions such as the functions compiled into the .exe.
This has confused me somewhat and has forced me to build both the AppMain module and the Platform Code into the same exe file so they can use each others functions.
Is there any way I can create a header file (with all the function prototypes in) but they do not get implemented in the Platform code but rather they can be 'guaranteed' to be available at runtime?
Here is what I am trying to achieve in a high level view:
win32layer.cpp: (implements all the functions defined in Platform.h)
#include <AppMain.h>
int main(int argc, char** argv) {
//call AppMain
return AppMain(argc, argv);
[Code] ....
in this scenario of course I could not compile the platform functions as the application has not been created and thus appmain cannot call the platform functions because that has not been created etc....
Any way to overcome this?
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May 10, 2013
I would like to convert a float or double variable into unsigned char variable and back.
float number_float = 23.453f;
unsigned char* number_char = (unsigned char*)malloc(sizeof(float));
number_char = reinterpret_cast<unsigned char*> (&number_float);
float* number_float_0 = reinterpret_cast<float*>(&number_char);
I am not getting the same value back.. why?
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